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Toronto AES Bulletin

Jan 2002

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A Better Understanding Of Stereo Microphone Technique

The subject of stereo microphone techniques often leads to passionate discussion amongst recording engineers. Spaced omnis, MS, Blumlein, near-coincident . . . everyone seems to have a favourite technique and an explanation for why their system is the best. But what in fact are the differences? Geoff Martin helps clear things up with 3D plots of stereo pickup patterns of ideal microphones and commentary on real-world limitations.


Phantom image placement in the horizontal plane of a stereo playback system relies on one or both of two auditory components, these being interchannel amplitude and time differences. Simple mathematical analysis of various configurations is used to clarify how these components are employed by coincident and spaced microphone pairs to generate the reproduced sound stage. Various textbook configurations will be discussed, as well as the effects of real-world factors such as off-axis frequency response and early reflections on image position and quality. Audio demonstrations and three dimensional visual plots will be used to illustrate various points.

Biography - GEOFF MARTIN, Ph.D. (McGill)

Originally from St. John's, Newfoundland, Geoff Martin completed his Bachelor of Music in pipe organ at Memorial University of Newfoundland in 1990. He is a graduate of McGill's Masters program in Sound Recording and, in 2001, completed his doctoral studies in which he developed a method of simulating first reflections from quadratic residue diffusers for multichannel virtual acoustic environments.

A Faculty Lecturer for the Music Technology area, Dr. Martin teaches courses in new media, electronics, and electroacoustics. He is continuing his research in synthetic acoustics and is a member of the development team for McGill's new Centre for Interdisciplinary Research in Music, Media and Technology (CIRMMT). In addition, he maintains an active musical career as an organist, choral conductor and electroacoustic music composer.

Dr. Martin is the Papers Chairman for the upcoming 2003 International Conference of the Audio Engineering Society on multichannel audio to be held at The Banff Centre in Banff, Alberta.

Presented by Geoff Martin, McGill University
Date Tuesday, 22 January, 2002
Time 7:30 pm
Place Ryerson Eaton Lecture Theatre, Rogers Communications Building
Address 80 Gould Street, Toronto, ON corner of Gould and Church, one block east of Yonge St (Dundas Subway)
Pre-Meeting Dinner 5:30 pm Baton Rouge Restaurant - 218 Yonge St.
(in the Eaton Centre with an entrance off of Yonge St.)

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Originally posted: 14 Jan 2002
Last update: 14 Jan 2002